In a telephone receiver set, the communication is generally obtained through a twin wire telephone line.
When the telephone receiver set is in the waiting or rest position, the twin wire line is connected to the call warning device, generally a bell.
Upon a telephone call actuating the warning device, the user takes off the telephone handset and a switch disconnects the telephone line from the warning device and connects it to communication members, formed conventionally of a microphone and an earphone. Some telephone receiver sets comprise a device enabling the user to converse with his correspondent without having to take off the telephone handset. Such receivers, commonly called "hands free" sets, comprise a bistable switch which, at the time of reception of the telephone call, disconnects the telephone line from the warning device, generally under the action of a push-button operated by the user, and connects it to the amplified communication members. Such members include a microphone and a loudspeaker, and enable the user to converse while keeping both his hands free or, optionally, enabling a conversation to take place with more than one party. At the end of the conversation, the telephone line is disconnected from the communication members and is connected again to the warning device by a further actuation of the bistable switch.
There also exist on the market telephone receiver sets in which the "hands free" function is combined with the conventional function of picking up--replacing the telephone handset. The act of replacing the telephone handset may thus operate the "hands free" switch by actuating its control push-button through complex mechanical linkages.
A switch of the above-mentioned type is already known from German Patent No. DE-A-2 830 661. However, it is large in size because its locking-unlocking means are disposed at least partially outside the case of the switch.
German Patent No. DE-A-3 529 652 also describes a similar switch, but the mechanical construction of the switch is complicated, unreliable and expensive.
The present invention aims then at improving on these switches of the prior art and provides a compact double interaction switch, of simple reliable and economic constructions.